The proposed experiments investigate the function of known neuroanatomical pathways between areas of the neocortex by measuring the behavioral deficits that result from surgery that disrupts the pathways. The experiments also examine in monkeys and brain damaged humans the pathways involved in the recovery from these disconnection deficits. The research is theoretically and clinically important. Any effort toward understanding how the brain as a whole controls behavior must begin with a knowledge of the relationships operating between parts of the brain. Knowing the function of pathways which are still, or are no longer available to a brain damaged patient should predict the possibilities for recovery and point us toward the optimal program of therapy.